1. Field of the Invention
The present invention relates to a magnetic recording and reproducing apparatus for digital signals, such as a digital video cassette recorder for two types of magnetic recording media, metal evaporation tapes and metal powder tapes.
2. Description of the Prior Art
A digital audio tape system (DAT) is one of prior art recording and reproducing apparatuses for digital signals which uses only a recording head for overwrite recording, without using an eraser head (refer to The DAT Conference Standard Digital Audio Tape Recorder System; The DAT Conference, May 29, 1987).
DAT provides regions for recording pilot signals for detecting recording track position and data regions for recording information data. Further, it selects wavelengths of signals suitable for overwrite characteristic, or shortest and longest wavelengths of recording data patterns are set as described below so as to be suitable for overwrite characteristic. (For example, the longest wavelength is 2.66 .mu.m and the shortest one is 0.67 .mu.m in the data regions, while the longest wavelength is 24 .mu.m and the shortest one is 2 .mu.m in the regions for pilot signals.)
On the other hand, a new digital video cassette recorder standard for consumer use (referred to as DVD) was proposed in July 1993, and has been investigated in a HD Digital VCR Conference. (For example, T. Yamamitsu et al., Role of Storage in Multi-Media Age and High Density Recording Technology, Japan Applied Magnetism Society, 83th Meeting, 83-4, Jan. 25, 1994.)
DVC also assumes that signals are overwritten only with a recording head. Pilot signals for detecting recording tracks are generated by a digital modulation circuit with use of a data pattern, and they are superposed as a continuous signal over the whole track region. The shortest wavelength of information data is 0.49 .mu.m, while the longest wavelength is 22.1 .mu.m for data. Thus, DVC can overwrite signals at shorter and longer wavelengths than DAT. DVC uses only metal evaporation tapes suitable for overwrite characteristic.